Back pain represents the single most costly medical investment in the United States today--over 14 million dollars annually is often quoted as the medical cost of back pain, and most medical authorities agree that most back pain is not pathologic, and much chronic back discomfort is associated with faulty posture associated with prolonged sitting.
The anterior convexity of the lumbar spine, particularly the lower lumbar and upper sacral area, is the origin of the vast majority of back problems in human beings. It is well known that any mechanical flattening of the normal lumbar curve, often called the "lumbar lordosis", aggravates or produces many of the nonspecific syndromes of the lower lumbar area. While individual human beings normally can voluntarily project this curve while standing, walking, or lying face down, they generally can not do so while sitting with their back improperly supported by a flat or concave seat back or lying flat on the back for prolonged periods of time, and such situations often introduce dynamics leading to the loss of lumbar lordosis. Sitting in a softly cushioned, or improperly designed chair, or lying face up in a supine position on a mattress with improper support defeats the body's normal protective muscular control over the lower lumbar area.
This disclosure is directed primarily to problems of upholding the human body in a seating position. But many of the objectives and concepts also have application to the supine (lying down face up position). It is expected that those concepts which are transferrable will be recognized by those familiar with the field.
Referring to FIG. 1 in the drawings, a typical cross-section of a portion of a human body on a conventional seating arrangement is shown. As shown, the body is longitudinally vertical in accepted medical terminology, meaning that the axis of the human body is considered to be longitudinal from head to foot (cephalo-caudal). Planes taken perpendicular to this longitudinal axis are termed transverse. Such terms will be applied to the similarly associated portions of the apparatus and system of the invention described herein.
In this FIG. 1, a chair designated by the letter C is diagrammatically illustrated as including a generally horizontally disposed seat S and a vertically extending back B. It will also be noted in this diagrammatically illustration that the back B is oriented at an angular relationship to the seat which is slightly graded at a right angle; for example, it is customary in most chairs to provide an angular relationship on the order of 95.degree.-100.degree.. It will be noted that persons seated on such a chair C will in effect have a substantially unsupported portion of the posterior of their spines, since the chair back is generally a flat planar structure and has little, if any, capability to conform with the lumbar lordosis LL and cannot provide any support. It will be also noted that the spine is shown in a correct configuration to achieve lumbar lordosis and provide proper support for body weight. Consequently, in the absence of providing a lumbar cushion system 20 of this invention, a person's spine will be effectively unsupported and that person must then rely entirely upon proper geometrical positioning of the body that must be physically maintained by a particular person in order to prevent fatigue and avoid adversely affecting the spine. Without such support, there will be a substantial tendency for fatigue and possible accompanying complications as to spinal problems due to physical inability to maintain lumbar lordosis for prolonged time periods.
Another factor to consider in attaining a proper support configuration is the relative positioning of the pelvic bone structure indicated generally at H. The spinal column extends upwardly from this pelvic bone structure and, in a seated position, the latter is preferably oriented in the illustrated position such that it is tending to incline slightly forward. This is induced through the proper body positioning as is illustrated, and results in providing a positive, stable base from which the spine, extending in a relatively vertical position, will obtain the most comfortable and optimum support for carrying of the body weight.
While the spine is relatively unsupported in case of a conventional chair C having a straight back or worse concave, it will be seen that use of a lumbar cushion system 20 of this invention will result in the proper support of the most important lumbar and upper sacral regions. In this elevational side view, it will be seen that the lumbar cushion system 20 is uniquely adapted to be located at the proper elevational position with a base surface 21 disposed in supported relationship to the forwardly facing surface of the chair back B. This then places the convex lumbar supporting surface 22 of the system in forwardly facing relationship for supporting and contacting engagement with the posterior 19 of the seated person's body. When thus vertically oriented, as indicated, and constructed with the optimum geometrical design as devised in accordance with this invention, it will be seen that this structure now provides a surface against which the posterior body surface will rest and will tend to obtain the necessary vertical support. The above summarizes the prior art. The objective is to fill the lumbar lordosis with resilient material without pressure points. Individual control of size, position, resiliency, and adaptation to existing structures are parameters this invention provides.
It will be understood in this diagrammatic illustration of the utilization of the lumbar cushion system 20 of this invention, as will be explained in greater detail hereinafter, that the structure will incorporate means for attaching or maintaining the system at a proper vertical elevation on a chair back B relative to a seated person's back. This attachment means is essential in assisting and maintaining the structure at the desired elevation and thus enable the person to move without resulting in displacement of the structure to an improper and incorrect position.
The concept of providing a lumbar support device has been considered in the past and various constructions have been patented. The prior art U.S. Pat. Nos. 1,236,517--Wemple et al., 1,667,626--Epstein, 2,060,298--Gailey, and 2,894,565--Conner disclose various constructions and apparatus means to hold a back support in place. These various patents have disadvantages in that the mechanisms are cumbersome, relatively expensive, and are lacking in adjustment features that have been found to be beneficial.
In spite of the need and previous attempts to provide proper support for the lumbar lordosis, most seating apparatus is constructed with a "main frame" configured for appearances and a "generally, comfortable look". Consequently, there remains a need for a lumbar support system that can be added to the seating arrangements that have been and continue to be sold for use. In the sense that the lumbar support system is "carried" to the existing seating; i.e., is purchased as a separate entity, brought to the site of the chair, usually at a work station, secretary position, executive chair, or in automobiles and other vehicles, it may be considered as "portable".
Because of the concern for appearances, most seat backs are either straight or convex posteriorly in the opposite direction to a proper lumbar lordosis as considered in the longitudinal direction. Not infrequently, the seat back is too short and either flat or too convex (exagerated lumbar lordosis) so that the seat back only touches the person's back at isolated positions. Many office style secretarial chairs are particularly guilty of this latter defective design, resulting in painful pressure points as well as lack of anatomic support.
In addition to the correct curvature in the longitudinal direction, a proper contour transversely at positions along the lumbar lordosis is also very important. In addition, modern seat backs have erroneously placed an anterior bulge too low where it presses on the sensitive sacrum instead of filling the lumbar lordosis.